1. Field of the Invention
This invention relates to an optical disc recording apparatus for recording information signals on an optical disc by recording means for enabling information signals to be read optically using an optical pickup device.
2. Description of the Prior Art
As an optical disc enabling recording of information signals, there has hitherto been proposed a magneto-optical disc having a signal recording layer permitting so-called perpendicular magnetization. For recording information signals on the magneto-optical disc, a region of the signal recording layer on which to record the information signals is heated to a temperature not lower than the Curie temperature, by means such as irradiating a converged laser beam, whilst an external magnetic field is applied to this region. Since the coercivity of the region of the signal recording layer, thus heated to a temperature not lower than the Curie temperature, is substantially nil, the direction of magnetization of the heated region is inverted to follow that of the external magnetic field. Digitized information signals can be recorded in this manner by inverting the direction of magnetization of the signal recording layer.
An optical disc recording apparatus for writing the information signals on the above described magneto-optical disc includes a driving unit for holding and rotationally driving the magneto-optical disc, an optical pickup unit for irradiating the signal recording layer of the magneto-optical disc with a laser beam, and a magnetic field generating unit for applying an external magnetic field to the signal recording layer.
Meanwhile, if it is desired with the above described optical disk recording apparatus to simplify and reduce the size of the apparatus, a so-called disc loading mechanism, adapted for transporting the magneto-optical disc to the driving device within the optical disc recording apparatus, can not be employed. Thus the optical disc recording apparatus, adapted for meeting the demands for size reduction and simplification of the construction, is provided with a disc table on which the magneto-optical disc is loaded from above, and a hinge-type upper lid for holding the upper surface of the magneto-optical disc placed on the disc table and for preventing leakage of the laser beam to the outside.
With the above described optical disc recording apparatus, if the upper lid is opened during recording of the information signals, and an ejecting operation is performed, the magneto-optical disc can not be maintained in position with respect to the driving device, and thus the recording of the information signals is interrupted. In such case, the information signals recorded until such time can not be read.
That is, since the information signals to be recorded in the optical disc recording apparatus are digital signals, it is necessary to record, after the end of recording of the information signals, so-called table-of--contents data (TOC data) concerning the information recorded on the disc. These TOC data represent signals indicating addresses etc. of the recorded information on the magneto-optical disc. The information signals, the corresponding TOC data of which are not recorded, can not be read.